Refrigerator and control method thereof

ABSTRACT

A control method includes determining whether to perform a defrosting operation of an evaporator, closing a valve to prevent refrigerant from moving into the evaporator if implementation of the defrosting operation is determined, performing a refrigerant collecting operation, and opening the valve upon completion of the defrosting operation. Intercepting a flow path of the refrigerant to prevent the refrigerant from moving into the evaporator during defrosting prevents explosion due to leakage of the refrigerant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.2010-0074683, filed on Aug. 2, 2010 in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

Embodiments relate to a refrigerator in which a freezing compartment anda refrigerating compartment are respectively provided with evaporatorsto enable independent cooling of the freezing compartment and therefrigerating compartment, and a control method thereof.

2. Description of the Related Art

A refrigerator serves to keep food fresh at a low temperature for a longtime by lowering the interior temperature of a storage compartmentthereof via a refrigeration cycle in which refrigerant undergoescompression, condensation, expansion and evaporation.

Conventional refrigerators, in which a freezing compartment and arefrigerating compartment are respectively provided with evaporators,may be classified into parallel-cycle refrigerators using a 3-way valveto enable independent operation of the freezing compartment and therefrigerating compartment, and serial-cycle refrigerators in which theevaporators of the freezing compartment and the refrigeratingcompartment are connected in series without a valve.

The above described conventional refrigerators may have a risk ofexplosion if refrigerant leaks from a refrigerant pipe during defrostingof the evaporators of the freezing compartment and the refrigeratingcompartment.

In addition, the conventional cycle refrigerators may causedeterioration in cooling efficiency of the freezing compartment andincrease energy consumption because of a higher evaporation temperatureof the refrigerating compartment upon simultaneous cooling of thefreezing compartment and the refrigerating compartment.

SUMMARY

Therefore, it is one aspect to provide a refrigerator and a controlmethod thereof, in which a flow path to a freezing compartmentevaporator and a refrigerating compartment evaporator is interceptedduring defrosting, preventing explosion of the refrigerator.

It is another aspect to provide a refrigerator and a control methodthereof, which may increase cooling efficiency of a freezing compartmentupon simultaneous cooling of the freezing compartment and arefrigerating compartment.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the invention.

In accordance with one aspect, a refrigerator includes a compressor, acondenser to condense refrigerant compressed in the compressor, afreezing compartment evaporator and a refrigerating compartmentevaporator installed respectively in a freezing compartment and arefrigerating compartment to evaporate the condensed refrigerant intogas-phase refrigerant, a valve to open or close a flow path of therefrigerant, and a control unit to close the valve if implementation ofa defrosting operation of any one of the freezing compartment evaporatorand the refrigerating compartment evaporator is determined.

The valve may be a 3-way valve connected to a discharge pipe of thecondenser and suction pipes of the freezing compartment evaporator andthe refrigerating compartment evaporator.

The valve may be an On-Off valve connected to a discharge pipe of thecondenser and suction pipes of the freezing compartment evaporator andthe refrigerating compartment evaporator.

The control unit may determine whether to perform the defrostingoperation of the freezing compartment evaporator and the refrigeratingcompartment evaporator, closes the valve to prevent the refrigerant frommoving into the freezing compartment evaporator and the refrigeratingcompartment evaporator if implementation of the defrosting operation ofthe freezing compartment evaporator and the refrigerating compartmentevaporator is determined, performs a refrigerant collecting operation,and opens the closed valve upon completion of the defrosting operation.

The refrigerant collecting operation may be performed in such a mannerthat the compressor is operated in a closed state of the valve to movethe refrigerant distributed in the freezing compartment evaporator andthe refrigerating compartment evaporator into the condenser.

In accordance with another aspect, a control method of a refrigeratorincludes determining whether to perform a defrosting operation of afreezing compartment evaporator and a refrigerating compartmentevaporator, closing the valve to prevent refrigerant from moving intothe freezing compartment evaporator and the refrigerating compartmentevaporator if implementation of the defrosting operation of the freezingcompartment evaporator and the refrigerating compartment evaporator isdetermined, performing a refrigerant collecting operation, and openingthe closed valve upon completion of the defrosting operation.

Implementation of the refrigerant collecting operation may includeoperating the compressor in a closed state of the valve to move therefrigerant distributed in the freezing compartment evaporator and therefrigerating compartment evaporator into the condenser.

In accordance with another aspect, a refrigerator includes a freezingcompartment evaporator, a refrigerating compartment evaporator, afreezing compartment fan and a refrigerating compartment fan, which areindependently installed in a freezing compartment and a refrigeratingcompartment, and a control unit to reduce revolutions per minute of therefrigerating compartment fan upon simultaneous cooling of the freezingcompartment and the refrigerating compartment, wherein the freezingcompartment evaporator is located at a front end of the refrigeratingcompartment evaporator and is connected in series to the refrigeratingcompartment evaporator.

In accordance with another aspect, a control method of a refrigeratorincluding a refrigerating compartment evaporator, a freezing compartmentevaporator located at a front end of the refrigerating compartmentevaporator and connected in series thereto, a refrigerating compartmentfan and a freezing compartment fan to enable independent cooling of afreezing compartment and a refrigerating compartment, includesdetermining whether or not a freezing compartment and a refrigeratingcompartment are simultaneously cooled, and reducing revolutions perminute of the refrigerating compartment fan to reduce evaporationcapacity of the refrigerating compartment if simultaneous cooling of thefreezing compartment and the refrigerating compartment is determined.

In accordance with another aspect, a refrigerator includes a firstrefrigerant circuit, through which refrigerant discharged from acompressor moves toward an entrance of the compressor by way of acondenser, a valve, a first expansion device, a first evaporator and asecond evaporator, and a control unit to control opening/closing of thevalve according to whether or not a defrosting operation of the firstevaporator and the second evaporator is performed.

The control unit may determine whether to perform the defrostingoperation of the first evaporator and the second evaporator, close thevalve to prevent the refrigerant from moving into the first evaporatorand the second evaporator if implementation of the defrosting operationof any one of the first evaporator and the second evaporator isdetermined, perform a refrigerant collecting operation, and open theclosed valve upon completion of the defrosting operation.

The refrigerant collecting operation may be performed in such a mannerthat the compressor is operated in a closed state of the valve to movethe refrigerant distributed in the first evaporator and the secondevaporator into the condenser.

The valve may be an On-Off valve connected to a discharge pipe of thecondenser and suction pipes of the first evaporator and the secondevaporator.

The refrigerator may further include a second refrigerant circuit,through which the refrigerant discharged from the compressor movestoward a suction side of the compressor by way of the condenser, thevalve, a second expansion device and the second evaporator. The valvemay be a 3-way valve connected to a discharge pipe of the condenser andsuction pipes of the first evaporator and the second evaporator.

In accordance with another aspect, a control method of a refrigeratorincluding a first refrigerant circuit, through which refrigerantdischarged from a compressor moves toward an entrance of the compressorby way of a condenser, a valve, a first expansion device, a firstevaporator and a second evaporator, and a control unit to controlopening/closing of the valve according to whether or not a defrostingoperation of the first evaporator and the second evaporator isperformed, includes determining whether to perform a defrostingoperation of the first evaporator and the second evaporator, closing thevalve to prevent refrigerant from moving into the first evaporator andthe second evaporator if implementation of any one of the defrostingoperation of the first evaporator and the second evaporator isdetermined, performing a refrigerant collecting operation, and openingthe closed valve upon completion of the defrosting operation.

In accordance with a further aspect, a control method of a refrigeratorincluding a first refrigerant circuit, through which refrigerantdischarged from a compressor moves toward an entrance of the compressorby way of a condenser, a valve, a first expansion device, a firstevaporator and a second evaporator, a second refrigerant circuit,through which the refrigerant discharged from the compressor movestoward a suction side of the compressor by way of the condenser, thevalve, a second expansion device and the second evaporator, and acontrol unit to control opening/closing of the valve according towhether or not a defrosting operation of the first evaporator and thesecond evaporator is performed, the control method includes determiningwhether to perform a defrosting operation of the first evaporator andthe second evaporator, closing the valve to prevent refrigerant frommoving into the first evaporator and the second evaporator ifimplementation of any one of the defrosting operation of the firstevaporator and the second evaporator is determined, performing arefrigerant collecting operation, and opening the closed valve uponcompletion of the defrosting operation.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a front view illustrating an exterior configuration of arefrigerator according to an embodiment;

FIG. 2 is a front view illustrating an interior configuration of therefrigerator according to the embodiment;

FIG. 3 is a control block diagram of the refrigerator according to theembodiment;

FIG. 4A is a serial refrigerant circuit according to an embodiment;

FIG. 4B is a parallel refrigerant circuit according to an embodiment;

FIG. 5 is a flow chart illustrating the valve control of the refrigerantcircuit of FIGS. 4A and 4B;

FIG. 6 is a refrigerant circuit according to another embodiment;

FIG. 7 is a flow chart illustrating the fan control of the refrigerantcircuit of FIG. 6 upon simultaneous cooling of a freezing compartmentand a refrigerating compartment; and

FIG. 8 is a refrigerant circuit according to a further embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout.

Hereinafter, a refrigerator and a control method thereof according to anexemplary embodiment will be described in detail with reference to FIGS.1 to 8.

FIG. 1 is a front view illustrating an exterior configuration of therefrigerator according to the embodiment, and FIG. 2 is a front viewillustrating an interior configuration of the refrigerator according tothe embodiment.

Referring to FIGS. 1 and 2, the refrigerator according to the embodimentof the present invention includes a body 10 in which a freezingcompartment 12 and a refrigerating compartment 14 are defined, and doors13 and 15 hingedly coupled to the body 10 to open or close the freezingcompartment 12 and the refrigerating compartment 14 respectively.

The freezing compartment 12 and the refrigerating compartment 14 arehorizontally divided by a partition 11 provided in the body 10 toprohibit movement of cold air between the compartments 12 and 14. Afreezing compartment evaporator 32 and a refrigerating compartmentevaporator 34 are individually installed in a rear region of thefreezing compartment 12 and the refrigerating compartment 14, to enablecooling of the respective compartments 12 and 14.

FIG. 3 is a control block diagram of the refrigerator according to theembodiment.

Referring to FIG. 3, a control unit 110 is connected to an input unit121, a temperature sensing unit 122, and a defrosting sensing unit 123.

The input unit 121 serves to input a user control command to the controlunit 110 and is provided with a plurality of buttons including, e.g., amode selection button to control operations of the freezing compartmentand the refrigerating compartment, and a temperature setting button toset respective temperatures of the freezing compartment and therefrigerating compartment.

The temperature sensing unit 122 is mounted, e.g., to inner walls of thefreezing compartment and the refrigerating compartment. The temperaturesensing unit 122 serves to sense the interior temperature of thefreezing compartment and the refrigerating compartment and transmit thesensed temperature value to the control unit 110. The temperature valueconstitutes data to determine the operational condition (simultaneouscooling or individual cooling) of the freezing compartment and therefrigerating compartment.

The temperature sensing operation using the temperature sensing unit 122may be performed in response to a sensing command from the control unit110, or may be performed independently even without receiving thesensing command.

The defrosting sensing unit 123 may adopt a sensor, a resistance valueof which varies based on the temperature of the freezing compartmentevaporator and the refrigerating compartment evaporator.

Considering the principle of a defrosting sensing operation in detail,the freezing compartment evaporator and the refrigerating compartmentevaporator are frosted by moisture because they perform a coolingoperation as refrigerant received therein evaporates by absorbing heatfrom the surrounding air. The frosted evaporator may cause a variationin the resistance value of the sensor. Thereby, the control unit 100determines whether to perform a defrosting operation upon receiving avoltage or current signal corresponding to the resistance value of thesensor from the defrosting sensing unit 123.

The control unit 110 is also connected to a compressor drive unit 131, afan drive unit 132, a valve drive unit 133, a defrosting heater driveunit 134 and a display unit 135.

The compressor drive unit 131 drives a compressor based on a drivecontrol signal of the control unit 110. If the compressor is a linearcompressor, the compressor drive unit 131 performs, e.g., generation andapplication of a Pulse Width Modulation (PWM) signal for drive voltageapplication based on a command from the control unit 110.

The fan drive unit 132 drives a freezing compartment fan 132 a, arefrigerating compartment fan 132 b, and a condenser fan 132 c based ona drive control signal of the control unit 110. The fan drive unit 132may be a single unit as illustrated in FIG. 3, or may include aplurality of units corresponding to the respective fans 132 a, 132 b and132 c.

In the present embodiment, the fan drive unit 132 functions to reducerevolutions per minute of the refrigerating compartment fan 132 b uponsimultaneous cooling of the freezing compartment and the refrigeratingcompartment. This may reduce the evaporation capacity of therefrigerating compartment evaporator, thereby preventing an increase inthe evaporation temperature of the freezing compartment.

The valve drive unit 133 performs opening/closing of a valve based on adrive control signal of the control unit 110. The valve may be a 3-wayvalve or On-Off valve.

In the present embodiment, the valve drive unit 133 closes the valve tointercept a flow path to the freezing compartment evaporator and therefrigerating compartment evaporator if any one of the freezingcompartment and the refrigerating compartment is subjected to adefrosting operation. The valve drive unit 133 again opens the valve toenable movement of refrigerant upon completion of the defrostingoperation. Opening or closing the valve by the valve drive unit 133according to whether the defrosting operation is performed or not mayeliminate any risk of explosion due to leakage of refrigerant from arefrigerant pipe during the defrosting operation.

The defrosting heater drive unit 134 drives defrosting heaters providedin the freezing compartment and the refrigerating compartment. Thedefrosting heater drive unit 134 supplies heat to the freezingcompartment evaporator and the refrigerating compartment evaporatorbased on a drive control signal of the control unit 110. The suppliedheat acts to remove frost formed on the freezing compartment evaporatorand the refrigerating compartment evaporator.

The display unit 135 displays the operational state of the refrigerator,various setting values, temperature, and so on.

A memory unit 140 stores temperature control values and defrostingconditions based on the operational condition of the freezingcompartment and the refrigerating compartment determined by the controlunit 110. The memory unit 140 stores a control factor for a valvecontrol operation to intercept the flow path to the freezing compartmentevaporator and the refrigerating compartment evaporator during thedefrosting operation. The memory unit 140 also stores a control factorto reduce revolutions per minute of the refrigerating compartment fan132 b upon simultaneous cooling of the freezing compartment and therefrigerating compartment.

The control unit 110 determines whether to perform startup of therefrigerator by comparing the temperatures of the freezing compartmentand the refrigerating compartment sensed by the temperature sensing unit122 with preset temperatures stored in the memory unit 140.

If the temperature of the freezing compartment or the refrigeratingcompartment is higher than a preset temperature by a predetermined valueor more, the compressor is operated after load of the compartment iscalculated according to a temperature difference. The startup time ofthe refrigerator is the operation time of the compressor.

The control unit 110 also compares the defrosting signal transmittedfrom the defrosting sensing unit 123 with the defrosting conditionsstored in the memory unit 140. If any one(s) of the evaporators fulfillsthe defrosting conditions, the control unit 110 controls thecorresponding evaporator(s) to perform a defrosting operation. Thedefrosting conditions may be set by, e.g., a reference voltage value ora reference current value.

In the present embodiment, if it is determined to perform a defrostingoperation upon the freezing compartment and the refrigeratingcompartment, the control unit 110 transmits a valve closing controlsignal to the valve drive unit 133. After completion of the defrostingoperation, the control unit 110 again opens the valve, allowing therefrigerant to move into the freezing compartment evaporator and therefrigerating compartment evaporator.

In the present embodiment, the control unit 110 reduces revolutions perminute of the refrigerating compartment fan 132 b upon simultaneouscooling of the freezing compartment and the refrigerating compartment.

FIG. 4A is a serial refrigerant circuit according to an embodiment.

In FIG. 4A, the serial refrigerant circuit 200 according to theembodiment of the present invention includes a compressor 210, acondenser 220, a valve 230, an expansion device 240, a refrigeratingcompartment evaporator 250, and a freezing compartment evaporator 260.

The compressor 210 compresses suctioned low-temperature and low-pressuregas-phase refrigerant to discharge high-temperature and high-pressuregas-phase refrigerant.

The condenser 220 is connected to a high-pressure discharge pipe of thecompressor 210 and condenses the compressed high-temperature andhigh-pressure gas-phase refrigerant from the compressor 210 intoliquid-phase refrigerant via heat exchange with the surrounding air.

The valve 230 is an On-Off valve to open or close the flow path of therefrigerant having passed through the condenser 220.

In the present embodiment, the valve 230 opens or closes the flow pathto the refrigerating compartment evaporator and the freezing compartmentevaporator according to whether the defrosting operation of therefrigerator is performed or not.

The room-temperature and high-pressure liquid-phase refrigerant,condensed in the condenser 220, is introduced into the expansion device240 by way of the valve 230. The expansion device 240 includes acapillary tube or an expansion valve to expand and decompress theroom-temperature and high-pressure liquid-phase refrigerant intolow-temperature and low-pressure two-phase refrigerant in the mixture ofliquid-phase and gas-phase components.

The freezing compartment evaporator 260 and the refrigeratingcompartment evaporator 250 evaporate the expanded low-temperature andlow-pressure liquid-phase refrigerant from the expansion device 240 intogas-phase refrigerant by absorbing heat from the surrounding air,thereby supplying cold air. The freezing compartment evaporator 260 andthe refrigerating compartment evaporator 250 constitute a serialcirculation configuration to enable independent operation ofthe'freezing compartment and the refrigerating compartment.

In the serial refrigerant circuit 200, the refrigerant circulates in thesequence of the compressor 210→the condenser 220→the valve 230→theexpansion device 240→the refrigerating compartment evaporator 250→thefreezing compartment evaporator 260→the compressor 210.

In addition, the condenser 220 is provided with a condenser fan 221 anda condenser fan motor 222 to drive the condenser fan 221. Therefrigerating compartment evaporator 250 and the freezing compartmentevaporator 260 are respectively provided with a refrigeratingcompartment fan 252 and a freezing compartment fan 262 to blow cold airgenerated from the respective evaporators 250 and 260. Also, arefrigerating compartment fan motor 253 and a freezing compartment fanmotor 263 are provided respectively to drive the refrigeratingcompartment fan 252 and the freezing compartment fan 262, and defrostingheaters 251 and 261 are provided to remove frost formed on therefrigerating compartment evaporator 250 and the freezing compartmentevaporator 260.

FIG. 4B is a parallel refrigerant circuit according to an embodiment.

In FIG. 4B, the parallel refrigerant circuit 300 according to theembodiment of the present invention includes a compressor 310, acondenser 320, a valve 330, a first expansion device 341, a secondexpansion device 342, a refrigerating compartment evaporator 350, and afreezing compartment evaporator 360.

The valve 330 is a 3-way valve having a single entrance and two exits toselectively switch the flow path of the refrigerant having passedthrough the condenser 320 based on an operational mode (simultaneous orindividual operation of the freezing compartment). The single entranceis connected to a discharge pipe of the condenser 320 and the two exitsare connected respectively to the first expansion device 341 and thesecond expansion device 342.

In the present embodiment, the valve 330 opens or closes a flow path tothe refrigerating compartment evaporator 350 and a flow path to thefreezing compartment evaporator 360 according to whether the defrostingoperation of the refrigerator is performed or not.

In the parallel refrigerant circuit 300, the refrigerant circulates inthe sequence of the compressor 310→the condenser 320→the valve 330→thefirst expansion device 341→the refrigerating compartment evaporator350→the freezing compartment evaporator 360→the compressor 310, or inthe sequence of the compressor 310→the condenser 320→the valve 330→thesecond expansion device 342→the freezing compartment evaporator 360→thecompressor 310.

Other configurations are identical to those of FIG. 4A, and adescription thereof is replaced by that of FIG. 4A.

Hereinafter, a control method of the above described refrigerant circuitand effects thereof will be described.

A conventional refrigerant circuit control method may cause explosionduring a defrosting operation using a defrosting heater because ifleakage of explosive refrigerant occurs during driving of the defrostingheater, the temperature of the leaked refrigerant may rise to aspontaneous combustion point. The refrigerant circuit control methodaccording to the present embodiment, which may eliminate the explosionrisk of the conventional refrigerant circuit control method, will bedescribed hereinafter with reference to FIG. 5.

FIG. 5 is a flow chart illustrating the valve control of the refrigerantcircuit of FIGS. 4A and 4B.

First, if power is input to the refrigerator, the defrosting sensingunit senses a resistance value of the sensor that varies depending onthe temperature of the evaporator of the refrigerator, and transmits avoltage or current signal corresponding to the resistance value to thecontrol unit. The control unit compares the voltage or current signaltransmitted from the defrosting sensing unit with preset defrostingconditions, thereby determining whether to perform a defrostingoperation of the refrigerating compartment evaporator and the freezingcompartment evaporator (410).

If implementation of the defrosting operation of the freezingcompartment evaporator or the refrigerating compartment evaporator isdetermined, the control unit closes the valve before the defrostingoperation of the corresponding evaporator begins (420). This mayintercept movement of refrigerant to the refrigerating compartmentevaporator and the freezing compartment evaporator prior to thedefrosting operation.

After closing the valve in operation 420, a refrigerant collectingoperation is performed to collect and move the refrigerant distributedin the freezing compartment evaporator and the refrigerating compartmentevaporator into the condenser (430).

In the refrigerant collecting operation 430, the compressor is turned onin a closed state of the valve to allow the refrigerant distributed inthe refrigerating compartment evaporator and the freezing compartmentevaporator to be moved into the condenser. The refrigerant collectingoperation 430 may prevent the refrigerant from being present in therefrigerating compartment evaporator and the freezing compartmentevaporator.

Once the refrigerant collecting operation 430 is completed, thedefrosting operation of the refrigerating compartment evaporator or thefreezing compartment evaporator is performed (440), and the compressoris turned off.

After implementation of the defrosting operation 440, the control unitdetermines whether or not the defrosting operation is completed (450).If completion of the defrosting operation of the correspondingevaporator is determined, the control unit again opens the closed valve(460) and restarts the compressor.

With the valve control of the refrigerant circuit illustrated in FIG. 5,no refrigerant is present in the refrigerating compartment evaporatorand the freezing compartment evaporator during the defrosting operation,thereby eliminating any risk of explosion due to refrigerant leakage.

Meanwhile, the conventional refrigerant circuit and control methodthereof may cause deterioration in the cooling efficiency of thefreezing compartment upon simultaneous cooling of the freezingcompartment and the refrigerating compartment because the temperature ofthe refrigerating compartment is higher than the temperature of thefreezing compartment. This may make it difficult to store food fresh andmay increase energy consumption.

A refrigerant circuit and control method thereof to preventdeterioration of the cooling efficiency and the increased energyconsumption will be described with reference to FIGS. 6 and 7.

FIG. 6 is a refrigerant circuit according to another embodiment.

In FIG. 6, the refrigerant circuit 500 according to the presentembodiment includes a compressor 510, a condenser 520, an expansiondevice 530, a freezing compartment evaporator 540, and a refrigeratingcompartment evaporator 550.

In the refrigerant circuit 500 of the present embodiment, the freezingcompartment evaporator 540 is located at a front end of therefrigerating compartment evaporator 550 and is connected in series tothe refrigerating compartment evaporator 550. Thus, refrigerant iscirculated in the sequence of the compressor 510→the condenser 520→theexpansion device 530→the freezing compartment evaporator 540→therefrigerating compartment evaporator 550→the compressor 510. That is, asthe refrigerant is first supplied into the freezing compartmentevaporator 540 and thereafter, is supplied into the refrigeratingcompartment evaporator 550, it may be possible to prevent deteriorationin the cooling efficiency of the freezing compartment due to a higherevaporation temperature of the refrigerating compartment evaporator 550.

Further, the refrigerant circuit 500 of the present embodiment enablesomission of the valve, achieving cost reduction.

Other configurations are identical to those of FIG. 4A, and adescription thereof is replaced by that of FIG. 4A.

FIG. 7 is a flow chart illustrating the fan control of the refrigerantcircuit of FIG. 6 upon simultaneous cooling of the freezing compartmentand the refrigerating compartment.

First, it is determined whether or not the compressor is in operation(610). If it is determined that the compressor is not in operation, boththe freezing compartment fan and the refrigerating compartment fan arestopped (630). In this case, the temperature of each compartment of therefrigerator is a preset temperature or less.

On the other hand, if it is determined that the compressor is inoperation, it is determined whether or not cooling of the freezingcompartment is performed (620). If cooling of the freezing compartmentis being performed, it is determined whether or not cooling of therefrigerating compartment is performed (640).

The refrigerating compartment fan is controlled to reduce revolutionsper minute thereof upon simultaneous cooling of the freezing compartmentand the refrigerating compartment (660). In this case, the temperatureof each compartment of the refrigerator is a preset temperature or more.

If cooling of any one of the freezing compartment and the refrigeratingcompartment is being performed (640 and 650), revolutions per minute ofeach fan is kept normal (670).

With the control to reduce revolutions per minute of the refrigeratingcompartment fan upon simultaneous cooling of the freezing compartmentand the refrigerating compartment, the evaporation capacity of therefrigerating compartment evaporator may be reduced, thereby improvingthe cooling efficiency of the freezing compartment.

FIG. 8 is a refrigerant circuit according to a further embodiment.

Referring to FIG. 8, a compressor 710, a condenser 720, a valve 730, anexpansion device 740, a freezing compartment evaporator 750 and arefrigerating compartment evaporator 760 are connected to one anothervia a refrigerant pipe, thereby defining a single closed-looprefrigerant circuit. Other configurations are identical to those of FIG.4A, and a description thereof is replaced by that of FIG. 4A.

In the present embodiment, the valve 730 is an On-Off valve to preventexplosion due to leakage of refrigerant from the refrigerant pipe duringdefrosting. The valve 730 is closed before the defrosting operation ofany one of the refrigerating compartment evaporator and the freezingcompartment evaporator begins. Then, the valve 730 is again opened uponcompletion of the defrosting operation of the corresponding evaporator,enabling movement of refrigerant.

To allow the refrigerant to be supplied first into the freezingcompartment evaporator 750, the freezing compartment evaporator 750 islocated at a front end of the refrigerating compartment evaporator 760and is connected in series to the refrigerating compartment evaporator760. Also, to prevent the temperature of the freezing compartment fromrising upon simultaneous operation of the freezing compartment and therefrigerating compartment, a control operation to reduce revolutions perminute of a refrigerating compartment fan 762 is performed. Thereby, theevaporation capacity of the refrigerating compartment evaporator 760 isreduced, restricting an increase in the evaporation temperature of therefrigerant in the freezing compartment and the temperature of therefrigerant suctioned into the compressor. This may improve the coolingefficiency of the freezing compartment and reduce energy consumption ofthe refrigerator.

The refrigerator and the control method thereof according to theexemplary embodiments have been described in detail. Although the doubledoor type refrigerator in which the doors are provided side by side atthe freezing compartment and the refrigerating compartment has beendescribed, the embodiments are also applicable to a top mount typerefrigerator in which a freezing compartment is located in an upperregion of the refrigerator, and a bottom freezer type refrigeratorhaving triple doors.

As is apparent from the above description, a refrigerator and a controlmethod thereof according to the embodiment may intercept a refrigerantflow path to a refrigerating compartment evaporator and a freezingcompartment evaporator during defrosting, thereby preventing explosiondue to leakage of refrigerant.

Further, as a result of locating the freezing compartment evaporator ata front end of the refrigerating compartment evaporator and connectingthe freezing compartment evaporator to the refrigerating compartmentevaporator in series, it may be possible to reduce revolutions perminute of a refrigerating compartment fan upon simultaneous cooling ofthe freezing compartment and the refrigerating compartment, resulting inan improvement in the cooling efficiency of the freezing compartment.This may achieve energy reduction and also, may achieve cost reductiondue to omission of a valve to open or close the refrigerant flow path.

Although a few embodiments have been shown and described, it would beappreciated by those skilled in the art that changes may be made inthese embodiments without departing from the principles and spirit ofthe invention, the scope of which is defined in the claims and theirequivalents.

1. A refrigerator comprising: a compressor; a condenser to condenserefrigerant compressed in the compressor; an evaporator to evaporate thecondensed refrigerant; a valve to open or close a flow path of therefrigerant; and a control unit to close the valve upon a defrostingoperation of the evaporator.
 2. The refrigerator according to claim 1,wherein the control unit determines whether to perform the defrostingoperation of the evaporator, closes the valve to prevent the refrigerantfrom moving into the evaporator if implementation of the defrostingoperation of the evaporator is determined, performs a refrigerantcollecting operation, and opens the closed valve upon completion of thedefrosting operation.
 3. The refrigerator according to claim 2, whereinthe refrigerant collecting operation is performed in such a manner thatthe compressor is operated in a closed state of the valve to move therefrigerant distributed in the evaporator into the condenser.
 4. Therefrigerator according to claim 1, wherein the evaporator includes afreezing compartment evaporator and a refrigerating compartmentevaporator.
 5. A control method of a refrigerator including acompressor, a condenser, an evaporator and a valve, the control methodcomprising: determining whether to perform a defrosting operation of theevaporator; closing the valve to prevent refrigerant from moving intothe evaporator if implementation of the defrosting operation of theevaporator is determined; performing a refrigerant collecting operation;and opening the closed valve upon completion of the defrostingoperation.
 6. The control method according to claim 5, whereinimplementation of the refrigerant collecting operation includesoperating the compressor in a closed state of the valve to move therefrigerant distributed in the evaporator into the condenser.
 7. Thecontrol method according to claim 5, wherein the evaporator includes afreezing compartment evaporator and a refrigerating compartmentevaporator.
 8. A refrigerator comprising a freezing compartmentevaporator, a refrigerating compartment evaporator, a freezingcompartment fan and a refrigerating compartment fan, which areindependently installed in a freezing compartment and a refrigeratingcompartment, the refrigerator further comprising: a control unit toreduce revolutions per minute of the refrigerating compartment fan uponsimultaneous cooling of the freezing compartment and the refrigeratingcompartment, wherein the freezing compartment evaporator is located at afront end of the refrigerating compartment evaporator and is connectedin series to the refrigerating compartment evaporator.
 9. A controlmethod of a refrigerator including a refrigerating compartmentevaporator, a freezing compartment evaporator located at a front end ofthe refrigerating compartment evaporator and connected in seriesthereto, a refrigerating compartment fan and a freezing compartment fanto enable independent cooling of a freezing compartment and arefrigerating compartment, the control method comprising: determiningwhether or not a freezing compartment and a refrigerating compartmentare simultaneously cooled; and reducing revolutions per minute of therefrigerating compartment fan to reduce evaporation capacity of therefrigerating compartment if simultaneous cooling of the freezingcompartment and the refrigerating compartment is determined.
 10. Arefrigerator comprising: a first refrigerant circuit, through whichrefrigerant discharged from a compressor moves toward an entrance of thecompressor by way of a condenser, a valve, a first expansion device, afirst evaporator and a second evaporator; and a control unit to controlopening/closing of the valve according to whether or not a defrostingoperation of the first evaporator and the second evaporator isperformed.
 11. The refrigerator according to claim 10, wherein thecontrol unit determines whether to perform the defrosting operation ofthe first evaporator and the second evaporator, closes the valve toprevent the refrigerant from moving into the first evaporator and thesecond evaporator if implementation of the defrosting operation of anyone of the first evaporator and the second evaporator is determined,performs a refrigerant collecting operation, and opens the closed valveupon completion of the defrosting operation
 12. The refrigeratoraccording to claim 11, wherein the refrigerant collecting operation isperformed in such a manner that the compressor is operated in a closedstate of the valve to move the refrigerant distributed in the firstevaporator and the second evaporator into the condenser.
 13. Therefrigerator according to claim 10, further comprising a secondrefrigerant circuit, through which the refrigerant discharged from thecompressor moves toward a suction side of the compressor by way of thecondenser, the valve, a second expansion device and the secondevaporator.
 14. A control method of a refrigerator comprising: a firstrefrigerant circuit, through which refrigerant discharged from acompressor moves toward an entrance of the compressor by way of acondenser, a valve, a first expansion device, a first evaporator and asecond evaporator; and a control unit to control opening/closing of thevalve according to whether or not a defrosting operation of the firstevaporator and the second evaporator is performed, the control methodcomprising: determining whether to perform a defrosting operation of thefirst evaporator and the second evaporator; closing the valve to preventrefrigerant from moving into the first evaporator and the secondevaporator if implementation of any one of the defrosting operation ofthe first evaporator and the second evaporator is determined; performinga refrigerant collecting operation; and opening the closed valve uponcompletion of the defrosting operation.
 15. A control method of arefrigerator comprising: a first refrigerant circuit, through whichrefrigerant discharged from a compressor moves toward an entrance of thecompressor by way of a condenser, a valve, a first expansion device, afirst evaporator and a second evaporator; a second refrigerant circuit,through which the refrigerant discharged from the compressor movestoward a suction side of the compressor by way of the condenser, thevalve, a second expansion device and the second evaporator; and acontrol unit to control opening/closing of the valve according towhether or not a defrosting operation of the first evaporator and thesecond evaporator is performed, the control method comprising:determining whether to perform a defrosting operation of the firstevaporator and the second evaporator; closing the valve to preventrefrigerant from moving into the first evaporator and the secondevaporator if implementation of any one of the defrosting operation ofthe first evaporator and the second evaporator is determined; performinga refrigerant collecting operation; and opening the closed valve uponcompletion of the defrosting operation.